In the conventional color thermal printer, each color of yellow (Y), magenta (M) and cyan (C) is successively recorded on recording paper which is being alternatively conveyed back and forth to juxtapose the three colors to form a full color image.
Among many processes proposed to control conveying of recording paper in recording, there is a process for realizing both precision conveying and reducing the margins at the front and rear ends of the recording paper, in which a conveying roller pair for conveying the recording paper is disposed in the vicinity of the thermal head and upstream of a length of the recording paper feeding direction, and in which the recording paper fed from a recording paper roll is fed backward while being image-recorded by the thermal head, and in which the recording paper is cut into separate image frames by a cutter after the completion of the recording.
In this case, in the backward conveying operation in which the recording paper fed from the recording paper roll is to be drawn backward, since the bight portion of the recording paper is brought into contact with the recording paper conveying path and generates a fold in the recording paper, it was necessary that the recording paper roll be driven in the direction of drawing backward so that the supplied recording paper be taken up.
In order to solve this problem, a process is proposed to provide a loop formation portion between the recording paper roll and the conveyor roller pair for stocking the recording paper in the form of a loop and the recording paper is accommodated within the loop formation portion when the recording paper is to be drawn backward. Also, in addition to the above, a proposition is made to provide brake means for applying a braking force on the recording paper and a dancer roller for making a loop of the returned recording paper by a spring action so that, when the recording paper is to be fed backward, the recording paper roll is held by the brake means not to be rotated, whereby the dancer roller maintains the recording paper in a loop-shape within the loop formation portion (patent document 1).
[patent document 1] Japanese Patent Laid-Open No. 2004-45669, FIG. 2